STRV-1a and -1b are a pair of microsatellites designed to test new space technologies and make measurements of the space environment and its effect on spacecraft systems. The emphasis of the project is on low-cost, short timescale access to space and the rapid dissemination of experimental data. Although built and operated by the UK's Defence Research Agency, many experiments are collaborative, involving the Ballistic Missile Defense Organization, the European Space Agency and Universities. After 2.5 years of operation the spacecraft has been turned over to NASA and the University of Colorado for communications experiments.

SpacecraftEach spacecraft has a cubic structure based on carbon/PEEK thermosplastic skinned aluminum honeycomb panels. Four GaAs solar panels provide 31-33W (BoL) to a 28V power distribution bus and 16 NiCd batteries. Platform requirements are approximately 19W, leaving 13W for payload operations. On-board data handling uses a GEC Plessey MIL-STD-1750 processor emplying radiation tolerant SOS technology. ESA CCSDS telemetry and telecommand standards are observed. Communications are through the S-band (2.2GHz); 125bps uplink and 1kbps downlink through a 1W omni-direction antenna. Both STRVs are spin-stablised at approximately 5rpm with attitude determination achieved via V-slit Sun and Earth sensors and analogue Sun sensors. Control is through magnetorquers and a cold gas thruster system.